<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>JavaScript下拉菜单</title>
    <style type="text/css">
        * {
            padding:0; 
            margin:0;
        }
        body {
            font-family:verdana, sans-serif; 
            font-size:small;
        }
        #navigation, #navigation li ul {
            list-style-type:none;
        }
        #navigation {
            margin:20px;
        }
        #navigation li {
            float:left;
            text-align:center;
            position:relative;
        }
        #navigation li a:link, #navigation li a:visited {
            display:block; 
            text-decoration:none; 
            color:#000; 
            width:120px; 
            height:40px; 
            line-height:40px; 
            border:1px solid #fff; 
            border-width:1px 1px 0 0; 
            background:#c5dbf2; 
            padding-left:10px; 
        }
        #navigation li a:hover {
            color:#fff;
            background:#2687eb;
        }
        #navigation li ul li a:hover {
            color:#fff;
            background:#6b839c; 
        }
        #navigation li ul {
            display:none;
            position:absolute; 
            top:40px;
            left:0;
            margin-top:1px;
            width:120px;
        }
        #navigation li ul li ul {
            display:none;
            position:absolute; 
            top:0px;
            left:130px; 
            margin-top:0;
            margin-left:1px;
            width:120px;
        }
    </style>
    <script type="text/javascript">
        function displaySubMenu(li) {
            var subMenu = li.getElementsByTagName("ul")[0];
			if(subMenu)
			{
				subMenu.style.display = "block";
			}
        }
        function hideSubMenu(li) {
            var subMenu = li.getElementsByTagName("ul")[0];
			if(subMenu)
			{
				subMenu.style.display = "none";
			}
        }
    </script>
</head>
<body>
    <ul id="navigation">
        <li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
           <a href="#">栏目1</a>
            <ul>
                <li><a href="#">栏目1->菜单1</a></li>
                <li><a href="#">栏目1->菜单2</a></li>
                <li><a href="#">栏目1->菜单3</a></li>
                <li><a href="#">栏目1->菜单4</a></li>
            </ul>
        </li>
        <li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
            <a href="#">栏目2</a>    
            <ul>
                <li><a href="#">栏目2->菜单1</a></li>
                <li><a href="#">栏目2->菜单2</a></li>
                <li><a href="#">栏目2->菜单3</a></li>
                <li><a href="#">栏目2->菜单4</a></li>
                <li><a href="#">栏目2->菜单5</a></li>
            </ul>
        </li>
        <li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
            <a href="#">栏目3</a>    
            <ul>
                <li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
                    <a href="#">栏目3->菜单1</a>
                    <ul>
                        <li><a href="#">菜单1->子菜单1</a></li>
                        <li><a href="#">菜单1->子菜单2</a></li>
                        <li><a href="#">菜单1->子菜单3</a></li>
                        <li><a href="#">菜单1->子菜单4</a></li>
                    </ul>
                </li>
                <li><a href="#">栏目3->菜单2</a></li>
                <li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
                    <a href="#">栏目3->菜单3</a>
                    <ul>
                        <li><a href="#">菜单3->子菜单1</a></li>
                        <li><a href="#">菜单3->子菜单2</a></li>
                        <li><a href="#">菜单3->子菜单3</a></li>
                    </ul>
                </li>
            </ul>
        </li>
		<li onmouseover="displaySubMenu(this)" onmouseout="hideSubMenu(this)">
            <a href="#">栏目4</a>    
		</li>
    </ul>
</body>
<script type="text/javascript">
	function getLeav2Num()
	{
		var menu = document.getElementById("navigation");
		var leav1 =  menu.childNodes;
		var len1 = leav1.length;
		var num = 0;
		for(var i = 0; i < len1; i++)
		{
			var ul = leav1[i].getElementsByTagName("ul")[0];
			if(ul)
			{
				num += ul.childNodes.length;
			}
		}
		return num;
	}

	function getLeav2Num2()
	{
		var menu = document.getElementById("navigation");
		var leav1 =  menu.childNodes;
		var len1 = leav1.length;
		var num = 0;
		for(var i = 0; i < len1; i++)
		{
			var ul = leav1[i].getElementsByTagName("ul")[0];
			try
			{
				num += ul.childNodes.length;
			}
			catch(e){}
		}
		return num;
	}
	//alert(getLeav2Num());
	//alert(getLeav2Num2());
</script>
</html>